An erection is caused by an influx of blood into sponge-like regions of tissue in the penis. The increased volume of blood in the penis causes it to become rigid and to increase in length and diameter. Many males suffer from erectile dysfunction. This condition is characterized by an inability to develop or maintain an erection that is of sufficient strength or duration to allow normal sexual intercourse.
U.S. Pat. No. 6,023,640 to Ross, which is incorporated herein by reference, describes the use of electromagnetic therapy to align the nutrients of the blood in a pearl cell formation in the direction of arterial flow. This is described as contributing, because of lessened flow resistance, to an increased volume of blood adequate for penis-engorgement.
U.S. Pat. No. 6,885,895 to Whitehurst, which is incorporated herein by reference, describes systems and methods for introducing one or more stimulating drugs and/or applying electrical stimulation to tissue affecting the penis to treat erectile dysfunction (for instance, following prostate surgery). The systems and methods are described as using at least one implantable system control unit (SCU) producing electrical pulses delivered via electrodes and/or producing drug infusion pulses, wherein the stimulating drug(s) are delivered via one or more pumps and infusion outlets.
PCT Publication WO 07/013065 to Gross, which is incorporated herein by reference, describes apparatus that includes a bifurcation stent comprising one or more electrodes, the stent configured to be placed in a primary passage and a secondary passage of a blood vessel, and a control unit, configured to drive the electrodes to apply a signal to a wall of the blood vessel, and to configure the signal to increase nitric oxide (NO) secretion by the wall. In an embodiment, the applied signal is described as being used to treat erectile dysfunction by functioning as a pump to enhance blood flow (e.g., for a diabetic patient), and/or by generating NO as a signaling molecule which enhances erection.
U.S. Pat. No. 5,372,573 to Habib, which is incorporated herein by reference, describes a method and apparatus for improving the flow of blood through a region of increased impedance. The method comprises assisting blood flow in said region by means of a pump placed in or around a blood vessel supplying blood to said region, and acting to pump blood in the required direction. The pump comprises, in one embodiment, a housing annularly surrounding a compressible conduit, said housing containing a plurality of flexible inflatable containers mounted for contact with said conduit (e.g., a blood vessel) and means for effecting sequential inflation and deflation of said containers so as to create a peristaltic pumping effect.
The following patents and patent applications, which are incorporated herein by reference, may be of interest:    U.S. Pat. No. 5,324,323 to Bui    U.S. Pat. No. 5,645,839 to Chobanian et al.    U.S. Pat. No. 5,800,502 to Boutos    U.S. Pat. No. 5,900,433 to Igo et al.    U.S. Pat. No. 5,904,712 to Axelgaard    U.S. Pat. No. 6,038,485 to Axelgaard    U.S. Pat. No. 6,058,331 to King    U.S. Pat. No. 6,086,527 to Talpade    U.S. Pat. No. 6,200,259 to March    U.S. Pat. No. 6,347,247 to Dev et al.    U.S. Pat. No. 6,463,323 to Conrad-Vlasak et al.    U.S. Pat. No. 6,810,286 to Donovan et al.    U.S. Pat. No. 6,824,561 to Soykan    U.S. Pat. No. 6,845,267 to Harrison et al.    U.S. Pat. No. 6,865,416 to Dev et al.    U.S. Pat. No. 6,871,092 to Piccone    U.S. Pat. No. 6,939,345 to KenKnight et al.    U.S. Pat. No. 7,206,637 to Salo    U.S. Pat. No. 7,229,403 to Schock et al.    US 2002/0103454 to Sackner et al.    US 2003/0036773 to Whitehurst et al.    US 2003/0204206 to Padua et al.    US 2004/0039417 to Soykan et al.    US 2004/0106954 to Whitehurst et al.    US 2006/0276844 to Alon    PCT Publication WO 04/014456 to Allen et al.    PCT Publication WO 06/094273 to White et al.    PCT Publication WO 07/064895 to Meyerhoff et al.    PCT Publication WO 07/106533 to Stern et al.    PCT Publication WO 07/113833 to Cahan et al.    PCT Publication WO 2006/064503 to Belsky et al.    PCT Publication WO 2006/123346 to Alon et al.    European Patent Application Publication EP 0 109 935 A1 to Charmillot et al.